-Late life decline in an individual's fertility and probablity of
survival.-Reduces and individual's fitness*Should be opposed by
Natural Selection

Examples of extended life span:

-Fly pop. can evolve longer life spans.-Bats live 3x as long as
other mammals of same size and similar metabolic rates.-Boosting
telomerase expression.

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Life span can be extended IF:

-Natural selection can lead to longer life spans.
-The physiological and genetic mechanisms for longer life already
exist.

Accumulation of: (2 cases)

-Deleterious mutations acting late in life.-Pleiotropic genes with
benefits early in life and costs late in life.

Late-acting Deleterious Genes only occurs if:

-Late-acting deleterious alleles occur at higher frequency than early
acting deleterious alleles then inbreeding depression resulting from
creation of deleterious homozygotes should be more severe late in life. -Confirmed
by Hughes in pattern of fruit flies.

Hughes' fruit fly experiment.

-Allowed flies to only reproduce for 4-5 days. -Caused late
acting mutations to become neutral.-Longevity declined rapidly, in
both large and small populations.

Virginia Opossum.

-Lives on mainland SE United States, and Sapelo Island. -Half of
natural possum deaths are caused by predators.-Sapelo Island has NO
mammalian predators. *Sidenote: Second year mainland female
offspring grow more slowly than first year. : Second
year island female offspring grow just as fast as first year.

-In humans, compared to other physiological capacity, reproductive
capacity declines earlier and more rapidly in women than men.*Menopause
is a life history adaptation associated with the contribution grandmothers make to feeding
their grandchildren.

Grandmother Hypothesis

-Suggests that menopause is a life history adaptation associated with the contribution grandmothers make to feeding their grandchildren.

1. A parent's reproductive effort in one year.2. Its survival or reproductive performance in future years.** Evidence found a (1) trade-off between current and future reproduction (2) trade-off between current reproduction and future survival.

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